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Digit Sum Magic Worksheet

Maths tricks trick 10: Digit-sum magic · Set 895 · 40 questions
TalentJR

The trick (Digits add to the 9 table): Add the digits you can see. Find the next number in the 9 table (9, 18, 27 …) above that total. The hidden digit is the difference. (Any number minus its digit sum is in the 9 table too.)

NameDateTime takenScore ___ / 40
  1. 1.Take 79 and take away the sum of its digits. What do you get?
  2. 2.2?40 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  3. 3.Take 32 and take away the sum of its digits. What do you get?
  4. 4.2?34 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  5. 5.Take 73 and take away the sum of its digits. What do you get?
  6. 6.?752 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  7. 7.?444 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  8. 8.?915 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  9. 9.Take 26 and take away the sum of its digits. What do you get?
  10. 10.?078 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  11. 11.?547 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  12. 12.Take 98 and take away the sum of its digits. What do you get?
  13. 13.29?8 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  14. 14.Take 83 and take away the sum of its digits. What do you get?
  15. 15.?89 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  16. 16.Take 23 and take away the sum of its digits. What do you get?
  17. 17.Take 72 and take away the sum of its digits. What do you get?
  18. 18.Take 15 and take away the sum of its digits. What do you get?
  19. 19.Take 99 and take away the sum of its digits. What do you get?
  20. 20.Take 96 and take away the sum of its digits. What do you get?
  21. 21.828? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  22. 22.35? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  23. 23.?115 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  24. 24.5?6 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  25. 25.?698 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  26. 26.4?56 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  27. 27.Take 86 and take away the sum of its digits. What do you get?
  28. 28.?997 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  29. 29.?406 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  30. 30.Take 58 and take away the sum of its digits. What do you get?
  31. 31.?10 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  32. 32.138? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  33. 33.6?87 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  34. 34.Take 21 and take away the sum of its digits. What do you get?
  35. 35.Take 12 and take away the sum of its digits. What do you get?
  36. 36.?186 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  37. 37.Take 35 and take away the sum of its digits. What do you get?
  38. 38.Take 28 and take away the sum of its digits. What do you get?
  39. 39.53? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  40. 40.591? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?

Answer key

  1. 63
  2. 3
  3. 27
  4. 9
  5. 63
  6. 4
  7. 6
  8. 3
  9. 18
  10. 3
  11. 2
  12. 81
  13. 8
  14. 72
  15. 1
  16. 18
  17. 63
  18. 9
  19. 81
  20. 81
  21. 9
  22. 1
  23. 2
  24. 7
  25. 4
  26. 3
  27. 72
  28. 2
  29. 8
  30. 45
  31. 8
  32. 6
  33. 6
  34. 18
  35. 9
  36. 3
  37. 27
  38. 18
  39. 1
  40. 3

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